codealike / arrayslice Goto Github PK

The implementation of unsafe optimization implies accessing fields on first use, create the local variables and let the optimization method to do its work.

Allowing the use of fields while unsafe in the general case (because of multithreading) should be allowed via the use of an attribute.

Currently the uses inside lambda expressions is a big unknown. It should work but we should do a throughly testing phase on those.

Running PEverify on the output of this https://github.com/Fody/FodyAddinSamples/tree/master/ArraySlicesSample

Results in

Error   4   Fody: PEVerify of the assembly failed.

Microsoft (R) .NET Framework PE Verifier.  Version  4.0.30319.33440
Copyright (c) Microsoft Corporation.  All rights reserved.

[IL]: Error: [C:\Code\Fody\FodyAddinSamples\ArraySlicesSample\bin\Debug\ArraySlicesSample.dll : AsyncErrorHandlerSample::Run][offset 0x0000005A] Unable to resolve token.
1 Error(s) Verifying C:\Code\Fody\FodyAddinSamples\ArraySlicesSample\bin\Debug\ArraySlicesSample.dll
    ArraySlicesSample

Control via class, method, indexer attribute if the corresponding code should be optimized.

public enum OptimizationMode
{
None,
Safe,
Unsafe
}

Sometimes optimization will introduce more instructions (preparation phase) than the ones than the times accessors are used, therefore penalizing on performance.

Examples like:

• Single getter or setter.
• Non loops accesses.
• Small loops (up to 4 loops in general)

ArraySlice should be able to find that out, and do not optimize the method is there is no net win in performance.

Currently ArraySliceBehaviorAttribute is supported only at the method level. It would be interesting to extend it to handle extended scopes like Assembly and Class.

Class will override Assembly
Method will override Class and Assembly.

When we have:

public readonly ArraySlice Field;

We can be sure that noone will modify it therefore it is safe to optimize its use.

This optimization will allow to optimize for the case where offsets start at 0 and therefore it wont be necesarry to add the offset to the stack.

The proper way to handle this is duplicating the method code and have 2 MSIL paths. One that will handle the (Offset == 0) condition and another one that will handle the (Offset != 0) condition. The concept itself is more or less the same used at optimizing compilers to handle Loop Unrolling.

Fody Version 2 is out and you will need to do an update for your addin to be usable with it

Specifically:

• Update to the newest Fody.Cecil nuget
• Change the min dependency ranged for Fody to be at least 2.0

Please ping me if u need help